1. Field
This disclosure relates generally to semiconductors, and more specifically, to a process for manufacturing a semiconductor device.
2. Related Art
Stress in a channel region of a transistor is used to improve the performance of the transistor by increasing the current drive strength of the transistor. It is well documented that a tensile stress in the channel of an N-channel transistor improves carrier mobility while a compressive stress in the channel of a P-channel transistor improves carrier mobility. Tensile stress in a transistor channel has been previously created by applying a stressor layer over the gate of the transistor. The stressor layer applies stress to the channel region of the transistor through the transistor's gate and source/drain regions. Lattice strain in a transistor's channel region increases the carrier mobility of transistor and increases the saturation current of the silicon transistors to improve performance. Silicon nitride is a well known stressor material.
Issues associated with the use of stressor layers include the cracking of such layers as semiconductor dimensions have become small. Stress fractures in stressor layers are prone to develop in areas of a transistor having angled structures such as at the corners of a transistor's gate. The current drive capability of transistors continue to need to increase to higher current values. Thus an improved transistor stressor which is reliable while continuing to improve transistor performance is desired.